Sometimes confused with black beetles
from the garden, cockroaches are distinguished
by their very long whip-like antennae, flat
oval bodies and rapid, jerky gait. The adult
German cockroach is 10 to 15mm long. The
Common or Oriental cockroach is 20 to 24mm
long. They are rarely able to survive out
of doors in the British climate, but thrive
around the heating ducts and boiler rooms
of large centrally heated buildings e.g.
hospital, bakeries, hotel and restaurant
kitchens, laundries and blocks of flats.
They cluster around pipes, stoves, sinks,
especially in humid areas. The German cockroach
carries its egg case, a small brown purse-like
capsule, until the 30 or more nymphs hatch
from it. The Oriental cockroach deposits
its 13mm long egg capsule on packaging,
sacking or in suitable dark crevices before
the 16 or 18 nymphs hatch out. Cockroaches
grow by stages - from "mini-cockroach"
nymphs to maturity in six to 12 months for
the Oriental cockroach, but only in as many
weeks in the case of the German cockroach.
Both species eat any sort of food and emerge
after dark, from their inaccessible harbourages,
to forage, contaminating food and food utensils,
or food preparation surfaces as they go.
They taint food with an obnoxious smell
and may be carriers of various diseases,
including serious food poisoning.
